A fluorinated compound is useful as a surface treating agent, since it has high lubricity, water/oil repellency, etc. By imparting water/oil repellency to a substrate surface by such a surface treating agent, stains on the substrate surface will easily be wiped off, and stain removability will be improved. Among such fluorinated compounds, a fluorinated ether compound having a poly(oxyperfluoroalkylene) chain wherein an etheric oxygen (—O—) is present in the middle of a perfluoroalkyl group, is excellent particularly in the fat and oil stain removability.
A surface treating agent containing such a fluorinated ether compound is useful for an application where a performance (abrasion resistance) such that water/oil repellency is less likely to be decreased even if repeatedly rubbed with a finger, and a performance (fingerprint stain removability) such that fingerprints attached on a surface can easily be removed by wiping, are required to be maintained for a long period of time, e.g. as a surface treating agent for a member constituting a surface to be touched with a finger, such as a touch panel.
Specifically fluorinated ether compounds of the following (1) to (3) are known as such fluorinated ether compounds.
(1) A fluorinated ether compound which has a poly(oxyperfluoroalkylene) chain and which has a perfluoroalkyl group at one terminal and has a hydrolysable silyl group at the other terminal (Patent Documents 1 and 2).
(2) A fluorinated ether compound which has a poly(oxyperfluoroalkylene) chain and which has a hydrolysable silyl group at each of both terminals (Patent Document 3).
(3) A mixture of a fluorinated ether compound which has a poly(oxyperfluoroalkylene) chain and which has a perfluoroalkyl group at one terminal and has a hydrolysable silyl group at the other terminal, and a fluorinated ether compound which has a poly(oxyperfluoroalkylene) chain and which has a hydrolysable silyl group at each of both terminals (Patent Document 4).